Water absorbing material and manufacturing method therefor

ABSTRACT

Provided is a water absorbing material having a granular core portion and a coating layer portion coating the granular core portion, which does not produce color before use and with which a test result can be determined only after use. In the water absorbing material, the coating layer portion is composed of 90 wt % to 96 wt % of a substrate and 10 wt % to 4 wt % of an excretion test material, the excretion test material contains a porous adsorbent having an adsorbance of 25 wt % or greater and including micropores, and an excretion test indicator adsorbed on the micropores of the porous adsorbent, and the excretion test indicator is added in an amount in the range of 0.015 wt % to 0.10 wt % relative to the total amount of the coating layer portion.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. continuation application filed under 35 USC111(a) claiming benefit under 35 USC 120 and 365(c) of PCT applicationPCT/JP2011/050649, filed on Jan. 17, 2011, which claims priority toJapanese Patent Application No. 2010-041057, filed on Feb. 25, 2010, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a granular water absorbing materialhaving a function to test urine in fluids such as excretions of humansor animals (hereinafter simply referred to as a “water absorbingmaterial”), and a production method, therefor.

BACKGROUND ART

Recently, the number of people who like pets and like animals has beenincreasing. and many pet owners pay attention to pet health just likehuman health. There is a limit to checking a change of the healthcondition of a pet by observation of pet's appearance, and therefore, inorder to readily discover such a change of the condition at an earlystage, an excretion treating material formed in a granular shape andcontaining a pH indicator has been used (Patent Literature 1).

CITATION LIST Patent Literature

[PLT 1]

-   JP 2000-333547A

SUMMARY OF INVENTION Technical Problem

However, since this excretion treating material is produced bydissolving an ink composition containing a pH indicator in water andspraying the diluted solution thereof onto the surface of the excretiontreating material formed in a granular shape, the excretion treatingmaterial is problematic in that, depending on the type of pH indicator,it may produce color before use due to reaction with moisture present inair or in the materials constituting the granular treating material.

The present invention was accomplished to solve the foregoing problem,and an object thereof is to provide a water absorbing material withwhich color production before use can be prevented and which can beinexpensively and readily produced, and a production method therefor.

Solution to Problem

To solve the foregoing problem, the water absorbing material of thepresent invention is a water absorbing material including a granularcore portion and a coating layer portion coating the granular coreportion, the coating layer portion is composed of 90 wt % to 96 wt % ofa substrate and 10 wt % to 4 wt % of an excretion test material, theexcretion test material contains a porous adsorbent having an absorbanceof 25 wt % or greater and including micropores, and an excretion testindicator (hereinafter referred to as a “test indicator”) adsorbed onthe micropores of the porous adsorbent, and the test indicator is addedin an amount in the range of 0.015 wt % to 0.10 wt % relative to thetotal amount of the coating layer portion.

Here, it is necessary to allow the aforementioned test indicator to beadsorbed on the porous adsorbent, and therefore, although the adsorptionmethod is not particularly specified, it is preferable that the testindicator is fixed while being in a solvent-dissolved state (inparticular, fixed as an ink composition).

Also, the test indicator is a reagent of any type that changes its colorupon reaction with excretion such as urine, and it is thus possible toperceive a change of health condition or the like. Urinary pH valuedetection indicators for detecting a urinary pH value (hereinafterreferred to as “urinary pH value test indicators”), urinary glucosedetection indicators, urinary protein detection indicators, urinaryoccult blood detection indicators, urinary urobilinogen detectionindicators, and like known indicators are usable.

Moreover, the water absorbing material of the present invention can beproduced according to a method for producing a multi-layer waterabsorbing material having a granular core portion and a coating layerportion that coats the granular core portion and contains an excretiontest indicator. The production method includes a granulation step ofproducing the granular core portion, an excretion test indicatoradsorption step of dissolving the test indicator in a solvent andallowing the dissolved test indicator to be adsorbed on a porousadsorbent, a coating material production step of adding the testindicator adsorbed on the porous adsorbent to a substrate to produce acoating material that constitutes the coating layer portion, and acoating step of coating a periphery of the granular core portion withthe coating material.

Regarding the water absorbing material of the present invention, a testindicator is not directly added, but the test indicator is adsorbed on aporous adsorbent. The porous adsorbent has the test indicator adsorbedin its gap portions, and therefore, leaching of moisture from thegranular core portion or the like can be blocked to some extent, and ifapertures are present in the gap portions, the gap portions can retainmoisture. Therefore, it is possible to prevent the highly reactive testindicator from producing color, which is caused by the reaction of thetest indicator, before use.

Since the test indicator is blended in the coating layer portion, thecoating layer portion promptly undergoes color change because it is incontact with the test indicator; and it is thereby possible to readilydetermine a test result in a short period of time.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a waterabsorbing material that does not produce color before use and with whicha test result can be determined only after use, and to produce a waterabsorbing material inexpensively and readily.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a flowchart showing the method for producing a water absorbingmaterial of the present invention.

DESCRIPTION OF EMBODIMENTS

One aspect (hereinafter referred to as an “embodiment”) of carrying outthe present invention will now be described in detail in reference tothe drawing, using as an example of a granular multi-layer waterabsorbing material for treating excretion (urine treating material) fora pet such as a cat or a dog.

The test indicator is described using a urinary pH value test indicatoras an example.

[Water Absorbing Material]

The water absorbing material of the present invention (hereinafterreferred to as the “present water absorbing material”) has a multi-layerstructure composed of a granular core portion for absorbing moisturefrom outside and a coating layer portion having a specific thickness andcoating the surface of the granular core portion.

(1) Granular Core Portion

It is sufficient that the granular core portion is formed in a pelletshape, and the granular core portion does not have to be, for example,perfectly spherical. The shape thereof is not limited to columnar(elongated), flat, or the like.

The granular core portion has water absorbability or waterretainability, and the materials and other features thereof are notlimited as long as a substance that inhibits testing when carrying outtesting of excretion (for example, in the case where a change of the pHvalue of excretion is to be observed, a substance that prevents pHchange) is not contained.

Usable examples include virgin pulp, toilet paper wastes, tissue paperwastes, facial paper wastes, cleaning paper wastes, cellulose waddingwastes, paper towel wastes, nonwoven-fabric wastes, and like organicwastes that do not inhibit testing of a pH value.

Also, bentonite, zeolite, titanium oxide, and such inorganic materialsas well as other materials can be used for the granular core portion.

It is possible to blend a deodorizing material, an odor eliminatingmaterial, a substance having bactericidal properties, a coloringsubstance, and a substance that can provide other effects withoutinhibiting water absorbability.

(2) Coating Layer Portion

The primary purpose of providing the coating layer portion is todemonstrate an action of causing grains of the water absorbing materialwet with excretion such as urine when used to adhere to each other so asto form an aggregate. In the case where the granular core portion isoriginally colored, the second purpose of providing the coating layerportion is to hide the color of the granular core portion before use bycoating the periphery thereof.

The coating layer portion is composed of a substrate and an excretiontest material.

<Substrate>

The role for achieving the purposes of the coating layer portion isplayed by the substrate. As for the materials thereof it is preferableto use, for example, an absorbent material, a water soluble materialhaving adhesion (hereinafter referred to as a “water soluble adhesivematerial”), a mixture of both materials, or a mixture of paper dust.

As these substances, known substances that do not inhibit testing whencarrying out testing of excretion are usable. Usable examples of theabsorbent material include CMC (carboxymethyl cellulose), polyvinylalcohol (PVA), starch (T-pregelatinized starch, dextrin, wheat starch,potato starch), and like materials having water absorbability.

Examples of the water soluble adhesive material include starchadhesives, sodium polyacrylate, and like highly absorbent materials.Usable as a starch adhesive that functions as such an adhesive arestarches such as potato starch, wheat starch, sweet potato starch, cornstarch (that does not inhibit testing), tapioca starch, rice starch,dextrin, and gelatinized (α) forms of these starches, acrylamide, PVA,carboxymethylcellulose, and sodium alginate, and two or more of thesematerials are usable in combination.

Examples of paper dust include virgin pulp, toilet paper, toilet paperwastes, tissue paper, tissue paper wastes, cleaning paper, cleaningpaper wastes, cellulose wadding, cellulose wadding wastes, paper towel,paper towel wastes, cotton-like pulp, cotton-like pulp wastes, paperdust generated in nonwoven fabric production, and a mixture ofpulverized products of two or more of these materials. All thesematerials are used after being pulverized into particulates having aparticle size of 0.5 millimeters or less, and preferably 0.3 millimetersor less.

<Excretion Test Material>

The excretion test material is a material in which an ink compositioncontaining a test indicator (hereinafter referred to as a “testindicator-containing ink composition”) is adsorbed on a porousadsorbent.

(Test Indicator-Containing Ink Composition)

The test indicator-containing ink composition is a composition in whicha test indicator is fixed to an ink composition.

Test Indicator

In the measuring of the pH value of excretion, the pH value of urine isdetected and, for example, persistent aciduria or alkaluria is detected,and a purpose of the measurement is to judge necessity of treatment oflithiasis or other diseases. Since the pH value of urine of a healthycarnivore such as a dog or a cat is 4.3 to 7.0, a pH value less than 4.3when diseased or a pH value greater than 7.0 when diseased can beidentified by color change relative to a pH value of 4.3 to 7.0 whennormal (when healthy), or that is, use of a urinary pH value testindicator that undergoes color change at the threshold pH value of 4.3or 7.0 allows identification thereof.

Also, since the pH value of human urine is 4.6 to 7.5 in a healthyperson who eats ordinary meals, a pH value of 4.6 to 7.5 when healthyand a pH value less than 4.6 when diseased or a pH value greater than7.5 when diseased can be identified by color change, or that is, use ofa urinary pH value test indicator that undergoes color change at thethreshold pH value of 4.6 or 7.5 allows identification thereof.

Examples of urinary pH value test indicators having a color change rangeat such a pH value, i.e., within the pH range of about 4.5 to 7.7include thymol blue, phenolphthalein, tropaeolin OOO, cresol red, phenolred, neutral red, bromothymol blue, bromocresol purple, bromophenol red,p-nitrophenol, methyl red, bromocresol green, tetrabromophenol blue,chlorophenol red, methyl orange, ethyl orange, bromophenol blue,brilliant yellow, congo red, bromocresol blue, and the like, andtherefore, depending on the purpose of detection, the aforementionedindicators can be used singly or as a combination of two or moreindicators.

In particular, in the case where the color change threshold is at a pHvalue of 4.3, it is preferable to use bromphenol blue or methyl orangeand bromocresol green dissolved in ethanol, and in the case where thecolor change threshold is at a pH value of 7.0, it is preferable to usebromthymol blue.

A universal indicator with which a pH value can be measured throughoutthe entire pH range can also be used.

Ink Composition

The test indicator-containing ink composition is a composition in whicha test indicator and a binder are fixed to a known ink composition. Inthe present embodiment, it can be prepared by, for example, dispersingor dissolving the urinary pH value test indicator and at least one ofcellulose and derivatives of the cellulose (hereinafter collectivelyreferred to as “cellulose”) in an organic solvent. Specifically,varnish, hydroxypropylcellulose, or the like that is a type of celluloseis added to the indicator and the mixture is dispersed or dissolved inan organic solvent, e.g., an alcohol such as methanol or ethanol, anaromatic hydrocarbon such as toluene, an ester such as propyl acetate,or the like to form the test indicator-containing ink composition.

For cellulose, preferable are cellose, methylcellulose, ethylcellulose,hydroxypropylcellulose, hydroxypropylmethylcellulose,carboxymethylcellulose, and the like in terms of wettability and ease ofvisual determination. In this case, as a solvent, it is preferable toselect a solvent that can stably dissolve or disperse the test indicatorand a resin that serves as the binder.

As binders, there are water soluble polymer compounds that do not affecttesting of excretion, that do not prevent color production of the testindicator, and that stabilize the produced color (natural hydrophilicpolymer compounds, semisynthetic hydrophilic polymer compounds) as wellas water insoluble polymer compounds that do not affect testing ofexcretion, that do not prevent color production of the test indicator,and that function to form a film. It is preferable to use both types ofbinder in combination.

Usable examples of the natural hydrophilic polymer compounds includesweet potato starch, potato starch, arum root powder, funori seeweed,sodium alginate, Abelmoschu manihot, tongaro gum, gum arabic, dextran,levan, nikawa glue, gelatin, casein, collagen, and the like.

Usable examples of the semisynthetic hydrophilic polymer compoundsinclude methylcellulose, hydroxypropylcellulose, hydroxyethylcellulose,carboxymethylcellulose, and like cellulosic derivatives, dialdehydestarch derivatives, and the like.

Usable examples of the water insoluble polymer compounds that functionto form a film include nitrocellulose, cellulose acetate,ethylcellulose, cellulose acetate butyrate, and like cellulosic resinsas well as polyester resin, alkyd resin, polyurethane resin, epoxyresin, acrylic resin, vinyl chloride resin, vinyl chloride copolymerresin, polyvinyl butyral, polyvinyl acetate emulsion, vinyl acetatecopolymer (such as vinyl acetate-acrylic ester) emulsion, acrylic estercopolymer emulsion, epoxy resin emulsion, synthetic rubber latex, andthe like. Among these polymer compounds that function to form a film,urethane resin and polyvinyl butyral, in particular, do not adverselyaffect the color change of the test indicator or the measurement of a pHvalue, and are thus preferable.

Moreover, known additives such as binders, stabilizers, or surfactantsthat enable formation of a uniform reagent layer (nonionic surfactants,anionic surfactants, cationic surfactants, amphionic surfactants,polyethylene glycol, or the like) can be added to the testindicator-containing ink composition.

Generally, the components of the test indicator-containing inkcomposition and their contents are as follows: indicator 1 wt % to 3 wt%, cellulose 1 wt % to 5 wt %, adhesive 10 wt % or less, with theremainder being composed of a solvent.

(Porous Adsorbent)

For the porous adsorbent, it is necessary to use an adsorbent includinga large number of micropores (fine apertures) and having a large surfacearea and an adsorbance of 25 wt % or greater. It is possible to useknown substances such as silica gel (so-called type A silica gel andtype B silica gel) (silicon dioxide) and zeolite (aluminosilicate). Inparticular, type B silica gel (an average absorbing surface area ofabout 450 (m²/g), an average micropore size of about 60

a micropore volume of about 0.75 (ml/g)) has a larger micropore size anda larger micropore volume than type A silica gel (an average absorbingsurface area of about 700 (m²/g), an average micropore size of about 24

a micropore volume of about 0.46 (ml/g)), and thus demonstrates a highlevel of adsorbability when adsorbing the test indicator-containing inkcomposition and is thus highly preferable.

Also, a penetrating agent or a swelling agent can be added to thecoating layer portion. As the penetrating agent, known substances suchas various surfactants can be used, and as the swelling agent, knownsubstances such as cellulose-based swelling agents can be used.

<Other Additives>

In the case where particles of a ground product of nonwoven fabric areused in the water absorbing material of the present invention, theparticles of the ground product adhere to each other and form anaggregate when excretion is discharged. Therefore, in order to make iteasy to handle the excretion treating material after discharging, anadhesive that is a starch adhesive having adhesion and not affectingtesting of urine is added. As such an adhesive, water soluble polymercompounds such as natural hydrophilic polymer compounds andsemisynthetic hydrophilic polymer compounds for use as a binder in thetest indicator-containing ink composition can be used.

Also, a penetrating agent or a swelling agent can be added to thecoating layer portion. As the penetrating agent, known substances suchas various surfactants can be used, and as the swelling agent, knownsubstances such as cellulose-based swelling agents can be used.

Proportions of Respective Materials

It is most preferable that the present water absorbing material hasproportions of its components of 80 wt % to 87 wt % of the granular coreportion and 20 wt % to 13 wt % of the coating layer portion inconnection with the size of the granular core portion, the thickness ofthe coating layer portion, and the proportion of water soluble dyeadded, which will be described below.

The coating layer portion is composed of 90 wt % to 96 wt % of asubstrate and 10 wt % to 4 wt % of an excretion test material.

It is necessary that the test indicator in the excretion test materialis added in an amount of 0.015 wt % to 0.10 wt % relative to the totalamount of the coating layer portion. Therefore, when the test indicatoris fixed to an ink composition, it is necessary to adjust the amounts ofthe solvent and other components such that the amount of the testindicator is within the aforementioned range and to determine the amountof the porous adsorbent according to the type thereof.

[Production Method]

Next, the method for producing a water absorbing material of the presentinvention is described in reference to FIG. 1.

The method for producing an excretion treating material of the presentinvention includes a granulation step (S1), an excretion test indicatoradsorption step (S2), a coating material production step (S3), a coatingstep (S4), a classification step (S5), and a drying step (S6).

(1) Granulation Step (S1)

This step is for forming a granular core portion.

In this step, components such as pulp wastes are pulverized with acrusher so as to have a specific size, and the pulverized components areplaced in a mixer and mixed such that specific proportions are attained.Then, water is added to increase the moisture content, and then themixed components are subjected to extrusion granulation. In this manner,a granular core portion forming operation is performed.

The coating material adheres to the periphery of the granular coreportion due to moisture present in the granular core portion. Therefore,when the moisture content of the granular core portion before formationof the coating layer portion is less than the lower limit, the materialsthat form the coating layer portion do not adhere to the periphery ofthe granular core portion. That is, when the moisture content of thegranular core portion is less than 20 wt %, the coating layer portion,which has a specific thickness necessary for demonstrating a specificaction, is not formed, and as a result, no multi-layer water absorbingmaterial is formed, separation of the coating layer portion occurs, noaggregate is created after use, and the appearance is poor. Therefore,such a moisture content is not preferable.

On the other hand, when the water content of the granular core portionexceeds 41 wt %, moisture of the granular core portion excessivelyleaches out into the coating layer portion during the formation of thecoating layer portion, and thus moisture comes into contact with thetest indicator and the test indicator produces colon Therefore, such amoisture content is not preferable.

Accordingly, in the case of performing the aforementioned extrudinggranulation, it is preferable to adjust the moisture content of thegranular core portion so as to be 20 wt % to 41 wt % (more preferably 20wt % to 25 wt %).

(2) Excretion Test Indicator Adsorption Step (S2)

This step is for preparing an excretion test material.

This step is for allowing a test indicator-containing ink compositionproduced by dissolving the test indicator in a solvent to be adsorbed ona porous adsorbent.

In this step, a test indicator-containing ink composition produced by aknown method is added dropwise little by little to, and is blended with,a porous adsorbent that has been processed into fine powder in order toallow the test indicator to be adsorbed on the porous adsorbent toprepare an excretion test material.

The proportions of the test indicator and the porous adsorbent aredetermined according to the adsorbance of the porous adsorbent. However,when the amount of the porous adsorbent added exceeds a specific amount,particles of the porous adsorbent are exposed from the surface layer ofthe coating layer portion, and thus such exposed portions project fromthe surface layer in the form of protrusions. Then, grains of the waterabsorbing material are brought into contact with each other duringpackaging and transportation, and thus the projecting portions separatefrom the base portions, creating a condition where, for example, adamaged surface layer portion is present. Therefore, such an amount isnot preferable.

It is necessary that the test indicator is added in an amount of 0.015wt % to 0.10 wt % relative to the total amount of the coating layerportion, and when the test indicator is fixed to the ink composition,the amounts of the solvent and other components are adjusted such thatthe test indicator is within the aforementioned range. Meanwhile, sinceevery porous adsorbent has its own largest adsorbance, the minimumrequired amount of the porous adsorbent is determined so as to allow anecessary test indicator to be adsorbed thereon, and therefore the testindicator-containing ink composition is adsorbed on the porous adsorbentof the amount thus determined.

(3) Coating Material Production Step (S3)

This step is for producing a coating material constituting the coatingportion.

This step is for producing a coating material by adding the excretiontest material prepared in the excretion test indicator adsorption stepto a substrate composed of specific materials and mixing them inspecific proportions so as to attain the desired amount of the testindicator.

Note that addition of desired materials such as a penetrating agent anda swelling agent other than the coating material and the excretion testmaterial to the coating layer portion is carried out in this step.

(4) Coating Step (S4)

This step is for forming the coating layer portion by coating theperiphery of the granular core portion with the coating material. Inthis step, the coating material is sprayed around the granular coreportion using a coating device or the like to form the coating layerportion. In this manner, an operation for producing a multi-layer waterabsorbing material is performed.

(5) Classification Step (S5)

This step is for classifying particles of the water absorbing materialso as to have a specific size.

In this step, the water absorbing material produced in the previous stepis sifted with a sieve having a specific mesh size to separate productsthat do not have a specific size. In this manner, an operation forobtaining only the products that have a specific size is performed.

(6) Drying Step (S6)

This step is for drying the obtained water absorbing material having aspecific size using a dryer.

In the case where the moisture content of the granular core portion ishigh during storage of the water absorbing material, moisture of thegranular core portion leaches out for an extended period of time, thusreacting with the test indicator, and color is produced. Therefore, thewater absorbing material is dried such that the water content of thegranular core portion is 3% or greater and 10% or less, which enablesprevention of color production during storage.

[Functional Effects]

Regarding the water absorbing material of the present invention, a testindicator is not directly added to the components of the coating layerportion, but the test indicator is first dissolved in a solvent andprocessed into a test indicator-containing ink composition, and, thenadsorbed on a porous adsorbent. The porous adsorbent has the testindicator-containing ink composition adsorbed in its gap portions, andtherefore. leaching of moisture from the granular core portion or thelike can be blocked to some extent, and if apertures are present in thegap portions, the gap portions can retain moisture, and it is thereforepossible to prevent the highly reactive test indicator from producingcolor, which is caused by the reaction of the test indicator, beforeuse. Since the test indicator is blended in the coating layer portion,the coating layer portion promptly undergoes color change because it isin contact with the test indicator, and it is thereby possible toreadily determine a test result in a short period of time.

So far, one preferable embodiment has been described, but the presentinvention is not limited to that embodiment, and design modificationscan be suitably performed without departing from the scope of thepresent invention. In the present embodiment, a description has beenprovided using as an example a water absorbing material for pets fortreating excretion. Needless to say, however, the water absorbingmaterial may be applied to humans and other animals.

In addition, a description has been provided using a urinary pH valuedetection indicator as an example of the test indicator, but the testindicator is not limited thereto, and urinary glucose detectionindicators, urinary protein detection indicators, urinary occult blood,detection indicators, urinary urobilinogen detection indicators, or likevarious indicators are usable.

Moreover, in the description provided above, the excretion testindicator adsorption step has been described as being performed afterthe granulation step, but these steps may be performed chronologicallyin parallel, and in addition to the aforementioned steps, other stepsmay be suitably added.

If a plurality of different types of test indicators are dissolved in asolvent and adsorbed on a porous adsorbent, and the mixture is added toa coating layer portion, multiple test results can be determined atonce.

EXAMPLES

To investigate the performance of the water absorbing material of thepresent invention, samples were prepared according to the productionmethod described below, and a color production test was carried out.

<Components>

Each sample used in the following test was produced according to theproduction method of the present invention, and was a multi-layer waterabsorbing material composed of a granular core portion and a coatinglayer portion. The weight ratio between the materials constituting thegranular core portion and the coating layer portion was 83 wt % to 17 wt%, and a 1000 g sample was produced.

(1) Granular Core Portion

Ingredients were virgin pulp (50 wt %, a water content of 8.0%), pulpsludge (49 wt %, a water content of 57.0%), and cornstarch (1 wt %, awater content of 9.0%).

(2) Coating Layer Portion

The coating layer portion was prepared by mixing a substrate (a mixtureof virgin pulp and carboxymethylcellulose) (provided that their mixingratio in wt % was the same) and an excretion test material.

The excretion test material was composed of a test indicator-containingink composition and a porous adsorbent.

As the test indicator-containing ink composition, a composition preparedby dissolving bromothymol blue (a test indicator) (manufactured byAdvantec Toyo Co., Ltd.) and a cellulose-based resin in an organicsolvent (industrial ethyl alcohol and methyl alcohol) was used (bothmanufactured by Toyo Ink MFG. Co., Ltd.), and samples were produced withvarying amounts of the test indicator added.

Fine powder of silica gel (B type) (manufactured by Hymo Co., Ltd.) wasused as the porous adsorbent.

<Samples>

The coating layer portion had either 96 wt % of a substrate and 4 wt %of an excretion test material or 90 wt % of a substrate and 10 wt % ofan excretion test material relative to the total weight.

Then, in either case, within the range of the aforementioned excretiontest material content, the amount of the test indicator was changed by0.005 wt % while satisfying the range of 0.005 wt % to 0.11 wt %relative to the total amount of the coating layer portion to adjust theamount of the ink composition blended, thus preparing a total of 44samples having different blending proportions.

<Observation Results>

Regarding each of the samples above, the extent of color production ofthe coating layer portion before and after use was visually inspected.As a result, no color production by the coating layer portion wasvisible in the samples before use that had the amount of the testindicator added relative to the total weight of the coating layerportion of 0.015 wt % to 0.10 wt %. Then, when a suitable amount of mockurine having a pH of 6.8 was added dropwise (corresponding to a sampleafter use), light green color was exhibited, and when a suitable amountof mock urine having a pH of 8.0 was added dropwise, blue color wasexhibited, thus providing favorable results (the same results wereobtained also when the proportions of the substrate and the excretiontest material were different).

On the other hand, regarding the samples in which the amount of the testindicator added relative to the total weight of the coating layerportion was 0.005 wt % and 0.010 wt %, both before use and when mockurine similar to that described above was added dropwise (correspondingto a sample after use), no clear color change was identified, thusfailing to give favorable results.

Also, regarding the samples in which the amount of the test indicatoradded relative to the total weight of the coating layer portion was0.105 wt % and 0.11 wt %, green color appeared on the coating layerportion before use, thus failing to give favorable results (the sameresults were obtained also when the proportion between the substrate andthe excretion test material was different).

According to the results presented above, it is clear that the amount ofthe test indicator added needs to be within the range of 0.015 wt % to0.10 wt % relative to the total amount of the coating layer portion.

REFERENCE SIGNS LIST

-   S1 Granulation step-   S2 Excretion test indicator adsorption step-   S3 Coating material production step-   S4 Coating step-   S5 Classification step-   S6 Drying step

The invention claimed is:
 1. A water absorbing material comprising agranular core portion and a coating layer portion coating the granularcore portion, the coating layer portion being composed of 90 wt % to 96wt % of a substrate and 10 wt % to 4 wt % of an excretion test material,the excretion test material containing a porous adsorbent having anabsorbance of 25 wt % or greater and including micropores, and anexcretion test indicator adsorbed on the micropores of the porousadsorbent, the excretion test indicator being added in an amount of0.015 wt % to 0.10 wt % relative to a total amount of the coating layerportion, and not being present in other than the porous adsorbent. 2.The water absorbing material according to claim 1, wherein the porousadsorbent is type B silica gel.